Paper advance error (“stitch” error) in a TIJ printer can result from a combination of drive train backlash together with coasting of the driven transport as the drives decelerate. This IP proposes a two-part paper advance profile to remedy this problem. The paper is advanced short of the final intended position. The final paper advance is made as a series of discrete steps which take up any backlash that may have occurred during the first advance.
Most low-cost TIJ printers advance paper incrementally through the print zone, such as by using a stepper motor or a position-controlled servo motor driving a shaft via a geartrain. Because the geartrain is designed for low cost manufacture, there is inevitably accumulated backlash in the drive train. This backlash can be a source of error in precision paper advances between carriage scans. Typical precision requirements are single standard of deviation errors of 20 μm for a paper advance of about 10 mm. Any backlash in the system can contribute an error if the motor deceleration occurs more rapidly than the driven roll deceleration. This is possible because the driven rolls are large diameter with significant inertia and low frictional drag. In this event, the load (driven roll) will “coast” through the geartrain backlash and stop at some indeterminate position.